Question
Given below are two statements: Statement I: Amino acids have a property of ionizable nature of –NH2 and –COOH groups, hence have different structures at different pH. Statement II: Amino acids can exist as Zwitterionic form at acidic and basic pH. In the light of the above statements, choose the most appropriate answer from the options given below:
Both Statement I and Statement II are correct.
Both Statement I and Statement II are incorrect.
Statement I is correct but Statement II is incorrect.
Statement I is incorrect but Statement II is correct.
Statement I is correct because amino acids possess a particular property involving the ionizable nature of –NH2 and –COOH groups, which causes their structure to change in solutions of different pH . Statement II is incorrect because the Zwitterionic form (a dipolar ion where the amino acid carries both a positive and negative charge but is electrically neutral) is pH-dependent . In acidic pH (high H+ concentration), the carboxyl group (COO-) accepts a proton to become COOH, making the molecule a cation; in basic pH (low H+ concentration), the amino group (NH3+) loses a proton to become NH2, making the molecule an anion [outside of sources]. Thus, the Zwitterionic form exists primarily at a specific pH (the isoelectric point) rather than at any acidic or basic pH .
This question aligns with the NEET BIOLOGY syllabus, specifically targeting concepts from Biomolecules. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.
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